AI Article Synopsis
- Human strains of Staphylococcus aureus produce two proteases called staphopain A and B, while avian strains produce staphopain C, which have varying roles in bacterial virulence.
- The study investigates the substrate preferences of these three proteases using various substrate libraries, revealing differences in their binding sites and activity patterns.
- Findings indicate that staphopain A has a different specificity from staphopains B and C, but all three can efficiently hydrolyze a range of substrates beyond their typical sequences, showing a degree of flexibility in their functions.
Article Abstract
Human strains of Staphylococcus aureus secrete two papain-like proteases, staphopain A and B. Avian strains produce another homologous enzyme, staphopain C. Animal studies suggest that staphopains B and C contribute to bacterial virulence, in contrast to staphopain A, which seems to have a virulence unrelated function. Here we present a detailed study of substrate preferences of all three proteases. The specificity of staphopain A, B and C substrate-binding subsites was mapped using different synthetic substrate libraries, inhibitor libraries and a protein substrate combinatorial library. The analysis demonstrated that the most efficiently hydrolyzed sites, using Schechter and Berger nomenclature, comprise a P2-Gly↓Ala(Ser) sequence motif, where P2 distinguishes the specificity of staphopain A (Leu) from that of both staphopains B and C (Phe/Tyr). However, we show that at the same time the overall specificity of staphopains is relaxed, insofar as multiple substrates that diverge from the sequences described above are also efficiently hydrolyzed.
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| http://dx.doi.org/10.1016/j.biochi.2011.07.020 | DOI Listing |
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